partly from Old English epistol and in part directly from Old French epistle, epistre (Modern French épitre), from Latin epistola "a letter," from Greek epistole "message, letter, command, commission," whether verbal or in writing, from epistellein "send to, send as a message or letter," from epi "to" (see epi-) + stellein in its secondary sense of "to dispatch, send" from PIE *stel-yo-, suffixed form of root *stel- "to put, stand," with derivatives referring to a standing object or place (see stall (n.1)). Also acquired in Old English directly from Latin as pistol. Specific sense of "letter from an apostle forming part of canonical scripture" is c. 1200.

1650s, from French épistolaire, from Late Latin epistolarius "of or belonging to letters," from Latin epistola "a letter, a message" (see epistle). In Middle English as a noun (early 15c.), "book containing epistles read in the Mass," from Medieval Latin epistolarium.

1640s, from Late Latin epistrophe, from Greek epistrophe "a turning about, twisting, a turning (of affairs), a moving up and down," from epi "upon" (see epi-) + strophe "a turning" (see strophe). In rhetoric, a figure in which successive phrases are followed by the same word of affirmation; also used in music. Related: Epistrophic.

"inscription on a tomb or monument," mid-14c., from Old French epitaphe (12c.) and directly from Medieval Latin epitaphium "funeral oration, eulogy," from Greek epitaphion "a funeral oration," noun use of neuter of epitaphios (logos) "(words) spoken on the occasion of a funeral," from epi "at, over" (see epi-) + taphos "tomb, funeral rites," from PIE root *dhembh- "to bury." Related: Epitaphial. Among the Old English equivalents was byrgelsleoð.

1610s, epocha, "point marking the start of a new period in time" (such as the founding of Rome, the birth of Christ, the Hegira), from Medieval Latin epocha, from Greek epokhe "stoppage, fixed point of time," from epekhein "to pause, take up a position," from epi "on" (see epi-) + ekhein "to hold" (see scheme (n.)). Transferred sense of "a period of time" is 1620s; geological usage (not a precise measurement) is from 1802.

1590s, a kind of lyric poem in which a short line follows a longer one (invented by Archilochus, also used by Horace), from Latin epodos, from Greek epodus "after-song, incantation," from epi "after" (see epi-) + odein "to sing" (see ode). Related: Epodic.

one whose name becomes that of a place, a people, an era, an institution, etc., 1833, from Greek eponymos "given as a name, giving one's name to something," as a plural noun (short for eponymoi heroes) denoting founders (legendary or real) of tribes, cities, etc.; from comb. form of epi "upon, (called) after," (see epi-) + onyma, Aeolic dialectal variant of onoma "name" (see name (n.)).

"giving one's name to," 1833; see eponym + -ous. Related: Eponymously. Alternative form eponymal is used in reference to the other classical eponymos, a title of certain magistrates in ancient Greece who gave their names to the years when they held office. Eponymic has been used in the sense "name-giving; pertaining to eponymic myths" as well as "of or pertaining to a classical eponymos."

1916, in reference to certain chemical compounds, from epi- + first element of oxygen. Epoxy- is used as a prefix in chemistry to indicate an oxygen atom that is linked to two carbon atoms of a chain, thus forming a "bridge" ("intramolecular connection" is one of the chemical uses of epi-). Resins from epoxides are used as powerful glues. Hence the verb meaning "to bond with epoxy" (1965). Related: Epoxied.

from Greek, literally e psilon "bare -e-, -e- and nothing else," so called by late grammarians in contradistinction to the diphthong -ai-, which had come to have the same sound. Greek psilon "smooth, simple" is of uncertain origin (Watkins suggests PIE root *bhes- (1) "to rub").

magnesium sulphate, 1770, obtained from Epsom water, the water of a mineral spring at Epsom in Surrey, England, the medicinal properties of which were discovered in Elizabethan times. The place name is recorded c.973 as Ebbesham, literally "Ebbi's homestead," from the name of some forgotten Anglo-Saxon. The mineral supply there was exhausted 19c.

late 14c., "identical in amount, extent, or portion;" early 15c., "even or smooth of surface," from Latin aequalis "uniform, identical, equal," from aequus "level, even, flat; as tall as, on a level with; friendly, kind, just, fair, equitable, impartial; proportionate; calm, tranquil," which is of unknown origin. Parallel formation egal (from Old French egal) was in use late 14c.-17c. Equal rights is from 1752; by 1854 in American English in reference to men and women. Equal opportunity (adj.) in terms of hiring, etc. is recorded by 1925.

late 14c., "evenness, smoothness, uniformity;" c. 1400, in reference to amount or number, from Old French equalité "equality, parity" (Modern French égalité, which form dates from 17c.), from Latin aequalitatem (nominative aequalitas) "equality, similarity, likeness" (also sometimes with reference to civil rights), from aequalis "uniform, identical, equal" (see equal (adj.)). Early 15c. as "state of being equal." Of privileges, rights, etc., in English from 1520s.

early 15c., "to make similar or the same; to balance or harmonize; distribute (ingredients) uniformly; reduce to evenness or smoothness; to set (a fracture)," from Latin aequatus "level, levelled, even, side-by-side," past participle of aequare "make even or uniform, make equal," from aequus "level, even, equal" (see equal (adj.)). Earliest use in English was of astrological calculation, then "to make equal;" meaning "to regard as equal" is early 19c. Related: Equated; equating.

late 14c., a term in astrology (from French équation, 14c.); general sense of "action of making equal" is from 1650s, from Latin aequationem (nominative aequatio) "an equal distribution, a sharing in common," noun of state from past participle stem of aequare (see equal (adj.)). Mathematical sense is from 1560s, on notion of equalizing the expressions; Chemistry sense is from 1807.

late 14c., from Medieval Latin aequator (diei et noctis) "equalizer (of day and night)," agent noun from Latin aequare "make equal" (see equate). When the sun is on the celestial equator, twice annually, day and night are of equal length. Sense of "celestial equator" is earliest, extension to "terrestrial line midway between the poles" first recorded in English 1610s.

royal officer, especially one charged with care of horses, 1590s, short for groom of the equirrie, from esquiry "stables" (1550s), from Middle French escuerie (Modern French écurie), perhaps from Medieval Latin scuria "stable," from Old High German scura "barn" (German Scheuer); or else from Old French escuier "groom," from Vulgar Latin scutarius "shield-bearer." In either case, the spelling was influenced by Latin equus "horse," which is unrelated.

"pertaining to or relating to horses or horsemanship," 1650s, formed in English from Latin equester (genitive equestris) "of a horseman, knightly," from eques "horseman, knight," from equus "horse" (see equine). As a noun, "one who rides on horseback," from 1786. The feminine form equestrienne is attested from 1848 (Century Dictionary calls it "circus-bill French"). An earlier adjective was equestrial (1550s).